Three-dimensional Atom Probe Analysis Research Articles

Systematic experimental and model-based evaluation of the synergistic effects of alloy composition and damage rate on the formation of Cr-rich precipitates in Fe–Cr–Al alloys under ion irradiation

Fourteen Fe–Cr–Al alloys with systematically varied Cr and Al compositions were irradiated at 350∘C to 0.24 dpa by 10.5 MeV self-ions as model alloys for the Fe–Cr–Al (oxide dispersion strengthened: ODS) alloys being developed as accident tolerant fuel (ATF) cladding for light water reactors. Three dose rates (8×10−6, 8×10−5, and 8×10−4 dpa/s) were selected to predict the formation behavior of Cr-rich precipitates (CrRP) under neutron irradiation conditions. The effects of Cr, Al composition, and dose rate on the CrRP formation behavior were evaluated using a three-dimensional atom probe (3DAP) analysis. The results showed that the CrRP number density, volume fraction, and Cr concentration increase with increasing Cr composition, decreasing Al composition, and decreasing dose rate. Multiple regression analysis showed that in addition to these primary effects, there was an interaction between them on the CrRP volume fraction: (1) the higher the Al composition, the smaller the increase in the CrRP volume fraction with increasing Cr composition, and (2) the lower the Cr composition, the smaller the increase in the CrRP volume fraction with the decreasing Al composition and dose rate. It was also highlighted that to understand the dose rate effect on the CrRP formation behavior under neutron irradiation, it is useful to examine the irradiation time dependence, including the effective use of thermal aging data as a limit to the zero dose rate, in addition to the dose-dependency perspective. In addition to the systematic database of CrRP-related quantities established in this study, these considerations should contribute to further developing and validating numerical prediction models.

Effect of retained austenite on impact-abrasion wear performance of high-strength wear-resistant steel prepared by dynamic partitioning process

The ductility and toughness of the high-strength wear-resistant steels can be improved by introducing retained austenite. However, the influence of retained austenite on the impact-abrasion wear resistance remains uncertain. This study investigates the effect of retained austenite on the impact wear performance of martensitic wear-resistant steel by introducing 5.2–9.2 vol% retained austenite through the dynamic partitioning (DP) process. The results display that the microstructures of the various DP-treated steels primarily consist of lath martensite and film-like retained austenite distributed between martensite laths. The three-dimensional atom probe (3DAP) analysis demonstrates that the retained austenite exhibits a significantly higher carbon concentration than the martensite, with carbon enrichment increasing gradually from the edge to the core of the retained austenite. In short-term impact wear tests (10 min), the weight loss of DP-treated steels is inversely proportional to the volume fraction of retained austenite. Conversely, in the long-term impact wear tests (20–90 min), it is positively proportional to the volume fraction of retained austenite. Initially, the strain-induced martensite transformed from retained austenite can absorb more impact energy, passivate the crack, and inhibit crack propagation, which is the dominant factor contributing to improved wear resistance. However, as impact wear progresses, the detrimental effects arising from the high hardness and poor plastic deformation ability of the strain-induced martensite become dominant, accelerating crack propagation during long-term impact wear tests. This study may provide insights into the microstructure design of the martensitic wear-resistant steels under impact wear conditions, specifically regarding the role of retained austenite.

Giant Thermoelectric Efficiency of Single-Filled Skutterudite Nanocomposites: Role of Interface Carrier Filtering.

The advantage of secondary-phase induced carrier filtering on the thermoelectric properties has paved the way for developing cost-effective, highly efficient thermoelectric materials. Here, we report a very high thermoelectric figure-of-merit of skutterudite nanocomposites achieved by tailoring interface carrier filtering. The single-filled skutterudite nanocomposites are prepared by dispersing rare-earth oxides nanoparticles (Yb2O3, Sm2O3, La2O3) in the skutterudite (Dy0.4Co3.2Ni0.8Sb12) matrix. The nanoparticles/skutterudite interfaces act as efficient carrier filters, thereby significantly enhancing the Seebeck coefficient without compromising the electrical conductivity. As a result, the highest power factor of ∼6.5 W/mK2 is achieved in the skutterudite nanocomposites. The nonuniform strain distribution near the nanoparticles due to the local lattice misfit and concentration fluctuations affect the heat carriers and thereby reduce the lattice thermal conductivity. Moreover, the three-dimensional atom probe analysis reveals the formation of Ni-rich grain boundaries in the skutterudite matrix, which also facilitates the reduction of lattice thermal conductivity. Both the factors, i.e., the reduction in lattice thermal conductivity and the enhancement of the power factor, lead to an enormous increase in ZT up to ∼1.84 at 723 K and an average ZT of about 1.56 in the temperature range from 523 to 723 K, the highest among the single-filled skutterudites reported so far.

Enhancement of magnetic properties and microstructural changes in TbCu7-type Sm-Fe-Co-Nb-B melt-spun ribbons

The effects of annealing conditions on magnetic properties, phase, and microstructural changes in Sm-Fe-Co-Nb-B melt-spun ribbons were investigated, and the dependence of magnetic properties on Sm and B composition was also investigated. SmxFe80.9−(x+y)Co16.4Nb2.7By amorphous ribbons were prepared by melt-spinning and then annealing. After annealing at 625 °C, the Sm6.2Fe66.4Co16.4Nb2.7B8.3 ribbons exhibited crystallization of hard-magnetic TbCu7-type phase, and the coercivity increased as the annealing time was increased to 9 h. The grain size of the TbCu7-type phase as estimated from transmission electron microscopy (TEM) images was 20–50 nm for ribbons annealed for 9 h. Three-dimensional atom probe (3DAP) analysis revealed that Nb and B became enriched at grain boundaries and tended to condense at the grain boundaries with increasing annealing time. Non-magnetic Nb and B enrichment at the grain boundaries in fine TbCu7-type grains thus promotes magnetic decoupling between TbCu7-type phases and suppresses domain wall propagation, resulting in high coercivity. Composition dependence on magnetic properties was investigated. Optimum annealing time tended to increase with increasing Sm content. The Sm6.7Fe65.9Co16.4Nb2.7B8.3 ribbons exhibited a maximum coercivity of 695 kA⋅m−1 by annealing at 625 °C for 21 h and subsequent slow cooling at a cooling rate of 4 °C⋅h−1. As B content decreased, coercivity decreased and remanence increased. The Sm6.2Fe68.7Co16.4Nb2.7B6.0 ribbons exhibited a high σr of 100 A⋅m2⋅kg−1 and moderate HcJ of 540 kA⋅m−1 after optimal annealing. An isotropic bonded magnet was fabricated from this ribbon. The bonded magnet exhibited high magnetic properties of Br = 0.82 T, HcJ = 538 kA⋅m−1, and (BH)max = 98 kJ⋅m−3, and small temperature coefficients of α(Br) = −0.06%⋅°C−1 and β(HcJ) = −0.27%⋅°C−1.

Microstructure evolution and coercivity mechanism of hydrogenation-disproportionation-desorption-recombination (HDDR) treated Nd-Fe-B strip cast alloys

In this paper, we systematically investigated the microstructure evolution and coercivity mechanism of hydrogenation-disproportionation-desorption-recombination (HDDR) treated Nd-Fe-B strip cast alloys by transmission electron microscopy (TEM) and three-dimensional atom probe (3DAP) analyses. The rod-like NdH2+x phases with diameters of 10–20 nm are embedded into α-Fe matrix, which hereditarily leads to textured grains in HDDR alloy. The migration of NdH2+x from Nd-rich region to α-Fe matrix during hydrogen absorption process contributes to the uniform redistribution of Nd-rich phases after HDDR treatment. The HDDR alloy with single domain grain sizes of 200–300 nm exhibits relatively low coercivity of 1.01 T that arises from pinning magnetic domain motion. The weak c-axis orientation of HDDR alloy results in a lower reverse magnetic field (coercivity) to reduce remanence to 0. Moreover, the direct contact of Nd2Fe14B grains and the high concentration of ferromagnetic elements (Fe content ≈ 66.06 at%, Co content ≈ 0.91 at%) in Nd-rich grain boundary layer lead to strong magnetostatic coupling effect among Nd2Fe14B grains. The nano-sized α-Fe inside Nd2Fe14B matrix makes the magnetization reversal easily and decreases the coercivity of HDDR alloy.

Impact of oxygen on band structure at the Ni/GaN interface revealed by hard X-ray photoelectron spectroscopy

To investigate the impact of oxygen on the band structure at the Ni/p-type GaN interface, the crystal structure and nanoscale impurity distributions were evaluated using transmission electron microscopy and three-dimensional atom probe (3DAP) analysis, respectively. These measurements revealed that the oxygen region existed approximately 5 nm from the GaN surface and that the oxygen concentration was equal to or higher than the Mg acceptor concentration. The band bending and photoelectron spectrum were then simulated using the Mg and oxygen concentration profiles obtained by 3DAP to consider the impact of the interfacial oxygen donors on the photoelectron spectrum measured using hard X-ray photoelectron spectroscopy (HAXPES). The precise band bending was then determined by fitting the simulated spectrum onto the experimental measurements. This showed that the oxygen donors at the interface modulated the band structure and decreased the energy barrier by at least 0.1 eV, which demonstrates the importance of considering the existence of oxygen at the interface. It is, therefore, essential to use techniques like 3DAP and HAXPES to evaluate both the nanoscale impurity distributions and the resulting band structure to fabricate higher-performance devices.

Significant reduction of phase-transition hysteresis for magnetocaloric (La1-xCex)2Fe11Si2Hy alloys by microstructural manipulation

First-order magnetostructural phase transitions are inevitably accompanied by large hysteresis, which evokes non-ignorable energy losses a main challenge for the utilization of giant magnetocaloric effect (MCE) materials in the emerging magnetic cooling technology. In this work, we present a novel approach to reduce the hysteresis and simultaneously to remain the giant entropy change in La-Fe-Si-based MCE alloys by microstructural manipulation. The microstructure evolution is comprehensively studied by high angle annular dark field-scanning transmission electron microscope, three-dimensional atom probe and geometric phase analysis. For the LaFe13-xSix system via co-doping of Ce and H atoms, we have observed the appearance of nanograins in size range of 5 – 50 nm that is totally different from the widely reported compositions. Such refinement can be ascribed to the release of internal stress caused by the inhomogeneous distribution of hydrogen atoms. With the formation of the nanocrystals in (La1-xCex)2Fe11Si2Hy alloys, the value of hysteresis loss can be monotonously reduced from 48.3 to 0.6 J kg−1. More importantly, the magnetostructural transition keeps an obvious first-order type, which leads to a large adiabatic temperature change of 2.03 K in 1.3 T upon 105 magnetic cycles, as well as a high reversible refrigeration capacity of 89.4 J kg−1 for (La0.6Ce0.4)2Fe11Si2Hy.

Effect of combined addition of Ag and Cu on the precipitation behavior for an Al-Mg-Si alloy

The effect of combined addition of Ag and Cu on the precipitation behavior for an Al-Mg-Si alloy was systematically investigated by atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and three-dimensional atom probe (3DAP) analysis. At the early aging stage, Ag and Cu atoms participate in the clustering process and accelerate the transformation of clusters to GP zones and β″ phases. In the peak aging stage, Ag atoms preferentially segregate at the β″/α-Al interfaces, while Cu atoms enter into the interior of the β″ phase and form a symmetry substructure, Cu sub-unit clusters. With prolonged aging, Ag atoms gradually incorporate in the β″ phase and form Ag sub-unit clusters. The incorporated Ag and Cu atoms can promote the formation of β′Ag, disordered QP1 and QP2 phases during the over aging stage. Almost all of these precipitates have a composite structure with various unit cells (β′, β′Ag, Q′ and C) or substructures (LDC, Cu sub-unit clusters, Ag sub-unit clusters), and Ag segregation is found in the interfaces of these precipitates. For the lath-like QP2 phase, Cu and Ag atoms segregate at the coherent and semi-coherent QP2/α-Al interfaces, respectively, which can reduce their strain energy and interfacial energy. These findings provide new insights in understanding the precipitate evolution of the Al-Mg-Si-Ag-Cu alloy, which is a potential alloy for automobile applications.

Microstructure and chemistry of the composite precipitate structure in Al-Li-Cu alloy

A combination of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging and three-dimensional atom probe analyses (3DAP) technologies was employed to accurately characterize the composite precipitate structure. Two types of the composite precipitate structure, i.e. δ′/T1 and δ′/T1/δ′ (T1-Al2CuLi and δ′-Al3Li), were observed. 3DAP analysis further confirmed the existence of this structure and solutes distribution was precise determined by concentration profiles. We also found that the coarsening of T1 was achieved by the nucleation of precursor on one side of matured T1 precipitate uncovered by δ′ precipitate and the coarsening of the inward T1 precipitate within the composite structure may would be depressed by the sideward δ′ precipitate.

Formation and crystallization behavior of Fe-based amorphous precursors with pre-existing α-Fe nanoparticles—Structure and magnetic properties of high-Cu-content Fe-Si-B-Cu-Nb nanocrystalline alloys

Structure, crystallization behavior, and magnetic properties of as-quenched and annealed Fe81.3Si4B13Cu1.7 (Cu1.7) alloy ribbons and effects of Nb alloying have been studied. Three-dimensional atom probe and transmission electron microscopy analyses reveal that high-number-density Cu-clusters and Pre-existing Nano-sized α-Fe Particles (PN-α-Fe) are coexistence in the melt-spun Cu1.7 amorphous matrix, and the PN-α-Fe form by manners of one-direction adjoining and enveloping the Cu-clusters. Two-step crystallization behavior associated with growth of the PN-α-Fe and subsequent nucleation and growth of newly-formed α-Fe is found in the primary crystallization stage of the Cu1.7 alloy. The number densities of the Cu-clusters and PN-α-Fe in melt-spun Fe81.3−xSi4B13Cu1.7Nbx alloys are gradually reduced with enriching of Nb, and a fully amorphous structure forms at 4 at.% Nb, although smaller Cu-clusters still exist. After annealing, 2 at.% Nb coarsens the average size (Dα-Fe) of the α-Fe grains from 14.0 nm of the Nb-free alloy to 21.6 nm, and 4 at.% Nb refines the Dα-Fe to 8.9 nm. The mechanisms of the α-Fe nucleation and growth during quenching and annealing for the alloys with large quantities of PN-α-Fe as well as after Nb alloying have been discussed, and an annealing-induced α-Fe growth mechanism in term of the barrier co-contributed by competitive growth among the PN-α-Fe and diffusion-suppression effect of Nb atoms has been proposed. A coercivity (Hc) ∝ Dα-Fe3 correlation has been found for the nanocrystalline alloys, and the permeability is inverse with the Hc.

Significant Reduction of Phase-Transition Hysteresis for Magnetocaloric (La 1-xCe x) 2Fe 11Si 2H y Alloys by Microstructural Manipulation

First-order magnetostructural phase transitions are inevitably accompanied by large hysteresis, which evokes non-ignorable energy losses a main challenge for the utilization of giant magnetocaloric effect (MCE) materials in the emerging magnetic cooling technology. In this work, we present a novel approach to reduce the hysteresis and simultaneously to remain the giant entropy change for La-Fe-Si-based MCE alloys by microstructural manipulation. The microstructure evolution is comprehensively studied by high angle annular dark field-scanning transmission electron microscope (HAADF-STEM), three-dimensional atom probe (3DAP) and geometric phase analysis (GAP). For the LaFe13-xSix system via co-doping of Ce and H atoms, we have observed the appearance of nano-sized grains (5 ~ 50 nm) that is totally different from the conventional compositions. Such refinement can be ascribed to the release of internal stresses caused by the inhomogeneous distribution of hydrogen atoms. With the increase of Ce content for (La1-xCex)2Fe11Si2Hy alloys, the value of hysteresis losses can be significantly reduced from 48.3 to 0.6 J kg-1. More importantly, the magnetostructural transition keeps the obvious first-order type, which leads to a large adiabatic temperature change of 2.2 K in 1.3 T upon 105 magnetic cycles, as well as a high refrigeration capacity of 89.4 J kg-1.

Influence of Deep Cryogenic Treatment on Microstructure and Properties of 7A99 Ultra-High Strength Aluminum Alloy

The hardness, toughness, wear resistance, and fatigue behavior of materials can be improved through a deep cryogenic treatment (DCT). During this treatment, low temperatures (−100 °C to −196 °C) are maintained and then increased to room or higher. In this work, an indirect-extrusion plate of 7A99 ultra-high strength aluminum alloy was subjected to a T6 (peak aging) treatment and a T6-DCT treatment. The influence of the T6-DCT treatment on the mechanical properties, grain morphologies, precipitates, and atom–cluster distribution was investigated via tensile testing, electron backscatter diffraction, transmission electron microscopy, and three-dimensional atom probe analysis. The tensile strength (maximum: 705 deep cryogenic treatment), yield strength (maximum: 678 MPa), and elongation (maximum: 14%) of the T6-DCT-treated alloy were higher than those of the T6-treated alloy. Moreover, the T6-DCT treatment resulted in (i) grain size refinement and increased uniformity of the microstructure (homogeneous distribution of η’-MgZn2- and η-phase precipitates), and (ii) reduced segregation degree of Zn, Mg, and Cu atoms in the matrix (fraction of small atom clusters (sizes: 10–20 nm, 20–50 nm) increased, fraction of large clusters (size: >1,000 nm) decreased). Therefore, DCT can refine the precipitates and increase the uniformity of the precipitate distribution, thereby improving the strength and plasticity of the alloy.

Relationship between the microstructure and properties of a peak aged Cu–Ni–Co–Si alloy

ABSTRACTThe microstructure and properties of a Cu–Ni–Co–Si alloy were investigated through high-resolution transmission electron microscopy and three-dimensional atom probe analysis after aging at 500°C for various times. Characterisation along different diffraction directions showed that precipitate morphology was disk shaped. The concentration profiles for Ni, Co, and Si were flattened in the precipitate interiors at levels of approximately 30, 35, and 35 at.-%, respectively. The co-segregation of Co was more significant than that of Ni and Si owing to the extremely low solubility in the matrix at room temperature. Theoretical calculations excellently agreed with the experimental data, which demonstrated that solid solution scattering and the Orowan bypass mechanism were the key reinforcement mechanisms for electrical and mechanical properties, respectively.HighlightsThe crystallography and morphology of precipitates in a peak aged Cu–Ni–Co–Si alloy are investigated in detail at different diffraction directions. Disk-shaped (Ni, Co)2Si precipitates are confirmed through 3DAP characterization.The distribution maps of Ni, Co, and Si alloying elements are investigated. Meanwhile, the segregation of the elements in the alloy are analyzed.The strengthening mechanism and conductivity curve of Cu–1.82 Ni–1.62 Co–0.86 Si alloy (wt-%) aged at 500°C for 2 h (peak aged state) are discussed, and theoretical calculations are in excellent agreement with the experimental data.

Influence of Zn on the distribution and composition of heterogeneous solute-rich features in peak aged Al-Mg-Si-Cu alloys

The distribution and composition of solute-rich features in peak aged Al-Mg-Si-Cu-(Zn) alloys was investigated via three-dimensional atom probe (3DAP) analysis. Our results show that a heterogeneous microstructure can be readily attained via Zn additions with concomitant improvement in the strength, elongation and strain hardening of peak aged alloy. Moreover, Zn partitioning into solute-rich features with a higher Mg/Si ratio (2.46–2.81) and higher number density were observed in the Zn-containing alloy and attributed to strong interactions among Mg, Si, Cu and Zn atoms. The formation of heterogeneous microstructure in the Zn-containing alloy was rationalized due to an increased tendency for clustering.

Three-dimensional atom probe analysis of boron segregation at austenite grain boundary in a low carbon steel - Effects of boundary misorientation and quenching temperature

Segregation of boron at random austenite grain boundaries with known misorientation angle in a boron-added low carbon steel quenched from austenite state at different temperatures was investigated quantitatively using three-dimensional atom probe. Boron segregation is reduced at low angle boundaries or low quenching temperatures. The latter result indicates that non-equilibrium boron segregation plays an important role and is enhanced at higher quenching temperature due to more excess vacancies and longer diffusion distance during quenching from higher temperature.

On the atomic model of Guinier-Preston zones in Al-Mg-Si-Cu alloys

Structural feature of equiaxed Guinier-Preston zones with the diameter of ∼2 nm in an Al-Mg-Si-Cu alloy has been systematically investigated by three-dimensional atom probe analyses, high-resolution electron microscopy and first-principles calculations. The results suggest that Si and Mg planes alternate along [001]Al with Cu atoms diversely substituting for some Si sites. An fcc-based Mg1(Si,Cu)1 model was then proposed for the first time, with expanded a, b and compressed c lattice parameters compared to Al. Meanwhile the structural evolution of Mg1(Si,Cu)1 → (Mg,Cu)1(Si,Cu)1 → β″-(Mg,Cu)1Mg4(Al,Cu)2Si4 is suggested.

Performance enhancement of blue light-emitting diodes with InGaN/GaN multi-quantum wells grown on Si substrates by inserting thin AlGaN interlayers

We have grown blue light-emitting diodes (LEDs) having InGaN/GaN multi-quantum wells (MQWs) with thin AlyGa1−yN (0 < y < 0.3) interlayers on Si(111) substrates. It was found by high-resolution transmission electron microscopy observations and three-dimensional atom probe analysis that 1-nm-thick interlayers with an AlN mole fraction of less than y = 0.3 were continuously formed between GaN barriers and InGaN wells, and that the AlN mole fraction up to y = 0.15 could be consistently controlled. The external quantum efficiency of the blue LED was enhanced in the low-current-density region (≤45 A/cm2) but reduced in the high-current-density region by the insertion of the thin Al0.15Ga0.85N interlayers in the MQWs. We also found that reductions in both forward voltage and wavelength shift with current were achieved by inserting the interlayers even though the inserted AlGaN layers had potential higher than that of the GaN barriers. The obtained peak wall-plug efficiency was 83% at room temperature. We suggest that the enhanced electroluminescence (EL) performance was caused by the introduction of polarization-induced hole carriers in the InGaN wells on the side adjacent to the thin AlGaN/InGaN interface and efficient electron carrier transport through multiple wells. This model is supported by temperature-dependent EL properties and band-diagram simulations. We also found that inserting the interlayers brought about a reduction in the Shockley-Read-Hall nonradiative recombination component, corresponding to the shrinkage of V-defects. This is another conceivable reason for the observed performance enhancement.

Atom probe analysis and magnetic properties of nanocrystalline Fe84.3Si4B8P3Cu0.7

We have investigated the microstructure and the magnetic properties of as-cast and flash annealed (4 s at 420 °C–560 °C) Fe84.3Si4B8P3Cu0.7 melt-spun ribbons. The scanning electron microscopy-electron backscattered diffraction (SEM-EBSD) analyses proved the existence of crystalline layer with the thickness of 1 μm in the as-cast state on both the wheel-contacted and the free surfaces of ribbons. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) patterns showed that the crystalline surfaces were textured. Moreover, the microstructure, composition and phase evolution of surface crystallization were studied using TEM and 3DAP which the spherulitic microstructure on the surface was demonstrated. Flash annealing above 420 °C led to a nanocrystalline microstructure of containing 10–15 nm α-Fe (Si) crystallites embedded in a residual amorphous matrix containing Fe, Si, B and P. Three-dimensional atom probe (3DAP) and high resolution transmission electron microscopy (HRTEM) analysis revealed that boron and phosphorous were rejected from α-Fe (Si) phase and enriched in the residual amorphous phase. The nucleation of the nanocrystals occurs heterogeneously from the 3–5 nm α-Fe crystals that were present in the as-cast state. The saturation magnetic induction (Bs) increases from Bs = 1.55 T in the amorphous state to Bs = 1.76 T after the crystallization. The saturation magnetostriction constant, λs, decreased from originally 35 ppm in the as-cast state to about 14 ppm with coercive fields in the range of Hc = 20–30 A/m.

Three-dimensional atom probe analysis and magnetic properties of Fe85Cu1Si2B8P4 melt spun ribbons

The effect of phosphorous on the microstructure and magnetic properties of as-spun and flash annealed (389–535°C for 7s) Fe85Cu1Si2B8P4 melt spun ribbons were investigated by three-dimensional atom probe (3DAP) and high resolution transmission electron microscopy (HRTEM) techniques. The formation of quasi-amorphous α-Fe clusters of 3–5nm size in an amorphous matrix were detected by HRTEM, despite the high quenching rate applied by high wheel speed used. Flash annealing of the as-spun ribbons gave rise to the formation of nanocrystalline α-Fe (Si) phase in amorphous matrix containing Fe, Si, B and P elements as detected by 3DAP. Comparing 3DAP analysis of the samples annealed at 445°C and 535°C revealed that the concentration of P and B in amorphous matrix were increased for the latter. Further, it was shown that P hardly solidified into nanocrystalline phase and partitioned in amorphous phase alongside B atoms leading to the further stabilization of amorphous matrix as confirmed by 3DAP analysis. The highest magnitude of saturation magnetic induction (Bs~1.85T) and the lowest coercive field (~10–20A/m) were obtained for the samples annealed above 445°C, for which noticeable reduction of saturation magnetostriction (λs) were also detected.

A study on the applicability of Si in low-Mo duplex stainless steel weld metals to improve the corrosion resistance

The applicability of Si in low-Mo duplex stainless steel weld metals is examined in terms of corrosion resistance and impact toughness. Nano-secondary ion mass spectrometry and three-dimensional atom probe analysis indicate that Si is enriched at the outermost layer in the form of Si-oxide a few nanometer thick, leading to a significant increase in critical pitting temperature without sacrificing the impact toughness. Improved corrosion resistance suggests that the thin oxide layer possibly acts as a diffusion barrier against aggressive ionic species.